indexed switch statement, or equivalent? .net, C#

Question

I want to build a method which accepts a string param, and an object which I would like to return a particular member of based on the param. So, the easiest method is to build a switch statement:

public GetMemberByName(MyObject myobj, string name)
{
   switch(name){
     case "PropOne": return myobj.prop1;
     case "PropTwo": return myobj.prop2; 
   }
}

This works fine, but I may wind up with a rather large list... So I was curious if there's a way, without writing a bunch of nested if-else structures, to accomplish this in an indexed way, so that the matching field is found by index instead of falling through a switch until a match is found.

I considered using a Dictionary<string, something> to give fast access to the matching strings (as the key member) but since I'm wanting to access a member of a passed-in object, I'm not sure how this could be accomplished.

• I'm specifically trying to avoid reflection etc in order to have a very fast implementation. I'll likely use code generation, so the solution doesn't need to be small/tight etc.

• I originally was building a dictionary of but each object was initializing it. So I began to move this to a single method that can look up the values based on the keys- a switch statement. But since I'm no longer indexed, I'm afraid the continuous lookups calling this method would be slow.

• SO: I am looking for a way to combine the performance of an indexed/hashed lookup (like the Dictionary uses) with returning particular properties of a passed-in object. I'll likely put this in a static method within each class it is used for.

Answer 1

Here's a quick mockup of something that could work for any class (using reflection rather than a switch statement):

public static object GetMemberByName<T>(T obj, string name)
{
    PropertyInfo prop = typeof(T).GetProperty(name);
    if(prop != null)
        return prop.GetValue(obj, null);

    throw new ArgumentException("Named property doesn't exist.");
}

Or an Extension Method version (which will still work on any object type):

public static object GetMemberByName<T>(this T obj, string name)
{
    PropertyInfo prop = typeof(T).GetProperty(name);
    if(prop != null)
        return prop.GetValue(obj, null);

    throw new ArgumentException("Named property doesn't exist.");
}

Obviously there's some additional error checking you might want to do, but this would be a start.

I also returned the type object from the methods for a reason. This allows the caller to handle casting the value however they see fit (if they need to cast at all).